Reconfigurable negative group delay circuit with low signal attenuation

A novel circuit scheme is presented for the design of reconfigurable negative group delay circuit (RNGDC) with very low signal attenuation (SA), which is based on a lossy coupled-line Microstrip (MS) resonator. Theoretical analysis indicates that reconfigurable characteristics in the proposed circuits can be obtained by tuning the resistance of the variable resistor, which is loaded at a specific point on the MS resonator. Based on the study of one-stage RNGDC, a two-stage RNGDC arranged in an anti-symmetrical manner is designed to provide an extended reconfigurable negative group delay range. To validate the performance of the proposed circuit scheme, the prototypes of one-stage and two-stage RNGDC have been designed working at a center frequency of 1.73 GHz. Measured results of the two-stage RNGDC exhibit a group delays variation of -2 ns to -10 ns with signal attenuation variation of -4.5 dB to -9.3 dB at the center frequency, which demonstrates much lower SA compared to the previously-reported RNGDCs.